Senators rejected this morning a binding three-year ban on earmarks proposed by Sen. Tom Coburn (R., Okla.). The vote failed 39 to 56, well short of the 67 votes required to advance the measure, but was the strongest showing ever by earmark opponents. Also, Coburn succeeded in his goal to get Senators on the record on pork spending.

As Cochran and other have made clear, everyone on that list — apart from Bennett (defeated in primary) and Voinovich (retiring) — should expect a primary challenge in their next election. Only Lugar is up in 2012, though he has been especially defiant in the face of criticism from the right, earning him a place in the heart of the The New York Times.

Even without a formal ban, pork-lovers are going to have a difficult time keeping the practice alive in the 112th Congress, with House and Senate Republicans voting to do away with earmarks on their own. Expect the GOP to continue its efforts to isolate Harry Reid and Senate Democrats on the issue.

It will be interesting to see how the Democratic leadership responds, specifically in regard to the pork-laden omnibus spending bill awaiting a vote. From Politico:

The massive bill already represents a serious bipartisan effort to reach a compromise by cutting up to $26 billion from President Barack Obama’s 2011 budget. And with nearly 40 senators supporting the moratorium, the Appropriations Committee leadership faces the threat of endless delays if some accommodation is not reached.

In private conversations, such steps are not being ruled out, and the combination of budget cuts and no binding legislative earmarks would be a sea change from where Congress stood just months ago. But with fiscal deadlines fast approaching — and the continuing election-year acrimony — it’s not clear the parties are prepared to grasp the potential deal before them.